Polyurethane (PU) is mainly applied in areas such as transportation, construction, textiles, electromechanics, aviation, medical treatment, coating, and synthetic leather, and is used in a wide variety of products with extensive applications, and has a rising demand. However, since PU is obtained from highly-toxic isocyanate and polyol, and the raw material of isocyanate is phosgene with even greater toxicity, significant harm is readily incurred to the human body during the raw material production process and coating processing. Moreover, isocyanate is sensitive to the humidity in the environment and reacts with water to form carbon dioxide gas, such that bubbles formation in the coating layer are occurred and sealing properties are reduced, and the usability of isocyanate are affected as a result.
Therefore, research efforts toward the development of a non-isocyanate polyurethane material are currently done. In many studies, non-isocyanate polyurethane (NIPU) materials prepared by cyclic carbonate and an amine compound have received the most attention.
NIPU is mainly obtained by reacting cyclic carbonate with an amine compound, and since the synthesis method thereof can avoid the use of an isocyanate compound having greater toxicity, the resulting product is a green material garnering increasing attention.
The key raw material of the non-isocyanate material is a cyclic carbonate compound, and the compound can be obtained by reacting carbon dioxide with an epoxy compound under the catalysis of a catalyst. Currently, the catalyst used in the synthesis of a cyclic carbonate compound has strict reaction conditions and low reaction conversion rate, and the thresholds of the cyclic carbonate process and the commercial mass production of the NIPU material are increased, and therefore how to effectively increase the reaction efficiency of an epoxy compound and carbon dioxide and develop a catalysis system having higher reactivity that can produce polycyclic carbonate under mild conditions have become an important research topic in recent years.